SAN FRANCISCO--In the old days, VMware made its money selling core virtualization software called a hypervisor that lets a computer run several operating systems simultaneously. Now it's moved beyond that.

"Over 80 percent of our revenue comes from outside of our hypervisor today," VMware President Diane Greene said in a press meeting at the company's VMworld show here Tuesday. "We've done a very effective job of building products that unlock the value of virtualization for our users."

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That's significant, given the competitive realities that face the company. The open-source Xen hypervisor today is available for free, and Microsoft plans to build a hypervisor code-named Viridian into its future Windows Server.

VMware initially sold core virtualization technology for desktops, then servers, but later added its Virtual Infrastructure software to manage virtual machines and other higher-level software. That software lets administrators handle tasks such as starting and stopping virtual machines, moving them from one physical machine to another through a feature called VMotion, backing them up and restarting them elsewhere in the event of a data center disaster, and monitoring resource use to make sure servers aren't either overtaxed or idle.

VMware's management software doesn't currently manage other hypervisors. "Our hypervisor has so much more functionality, it wouldn't make sense," Greene said. For example, 60 percent of the company's customers use VMotion, and that feature is only just arriving in product and has been removed from Microsoft's first version of Viridian.

Greene also offered a 10-year forecast, predicting that virtualization will become not merely accepted, as it is today in some circles, but omnipresent. "We do think virtualization will be ubiquitous on the hardware; and in automated data centers for someone running 3 servers to 3,000 servers, virtualization will just be a given," she said.